Heatsinks transfer heat away from a heat source to a surrounding environment. The transfer of heat occurs more effectively if the heatsink is fabricated from material that has a high coefficient of thermal conductivity. Such materials include copper and aluminum since these materials facilitate the conduction and dissipation of heat. Some heatsinks are configured with aluminum base and fins, copper base and fins, aluminum base with copper fins, or copper base with aluminum fins.
In order to increase thermal conductivity and decrease weight, some heatsinks are fabricated with graphite. Graphite weights less than aluminum and has better thermal conductivity. Graphite, however, is brittle and can flake or chip. As such, the base of a heatsink is typically not formed from graphite. Instead, graphite is more often used for the fins of the heatsink.
Metallic fins can be attached to the metallic base using various technologies, such as solder, epoxy, and swaging. These technologies, though, are not ideal for attaching graphite fins to a metal base. Solder does not achieve optimal wetting when used with graphite fins. Epoxy has a low thermal conductivity and thus is not well suited for heat transfer from the base to the fins. In addition, solder or epoxy can degrade over time and cause the fins to become loose or dislodged. In the process of swaging, a tool is used to plastically deform the metal base around the base of the fin in order to secure the fin to the base of the heatsink. During the swaging process, graphite flakes from the fins can dislodge and contaminate surrounding electrical circuitry.